Indoor unit for air-conditioning apparatus

ABSTRACT

An indoor unit for an air-conditioning apparatus includes a main body attached to an attachment portion, a heat exchanger attached to the main body and configured to exchange heat between air and refrigerant, a fan attached to the main body and configured to send, into a room, air subjected to heat exchange in the heat exchanger, and a front frame attached to the main body by using a screw. The front frame forms a fan casing that accommodates the fan between the front frame and the main body and through which air sent by the fan passes. The fan casing has an air outlet through which air is blown out, between a front air passage wall on a front side of the fan casing and a back air passage wall on a back side of the fan casing. The back air passage wall has, at a downstream terminal end, a recess into which the screw is inserted. The indoor unit further includes a screw cover covering the screw and attached to the recess. The screw cover has a hollow passing through in a laterally extending direction, and a chamber is formed by the hollow being held between side walls located on both sides of the recess in the front frame.

TECHNICAL FIELD

The present disclosure relates to an indoor unit for an air-conditioning apparatus, and the indoor unit has a main body to which a front frame is attached by using a screw.

BACKGROUND ART

As an indoor unit for an air-conditioning apparatus, an existing indoor unit having a main body to which a front frame is attached by using a screw has been known. In a housing made up of the main body and the front frame, for example, a heat exchanger and a fan are disposed, and the fan is accommodated in a fan casing. When the air-conditioning apparatus performs a cooling operation, the air cooled by the heat exchanger and air in a room may stay at a terminal end of the fan casing, and water in the air may thereby be solidified to cause condensation there.

Patent Literature 1 discloses an indoor unit for an air-conditioning apparatus. The indoor unit has a gap between a terminal end portion of a fan casing formed only of a main body of the indoor unit and a flange of a design panel that is a front frame. In a case of Patent Literature 1, the condensation water generated on the terminal end portion of the fan casing passes through the gap due to capillary action and flows into a condensation water-collecting portion of a panel bottom plate of the design panel. Thus, in Patent Literature 1, an attempt is made to suppress dripping of the condensation water generated on the terminal end portion of the fan casing to the outside of the indoor unit.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2008-224083

SUMMARY OF INVENTION Technical Problem

However, the occurrence of condensation itself is not suppressed by the technology disclosed in Patent Literature 1. A related-art indoor unit having a fan casing made up of both a main body and a front frame has also been known. In this case, the front frame has an air outlet from which air is blown out located between a front air passage wall on the front side relative to a passage, through which the air subjected to heat exchange in a heat exchanger passes, and a back air passage wall on the back side relative to the passage. Screws for attaching the front frame to the main body are disposed in recesses formed at a terminal end of the back air passage wall and are covered with screw covers. Here, because an upper face of each screw cover forms part of the back air passage wall, cold air is blown onto the upper face of the screw cover when an air-conditioning apparatus performs the cooling operation. It is impossible for an indoor unit similar to the indoor unit disclosed in Patent Literature 1 to suppress the occurrence of condensation itself even when a fan casing is made up of both a main body and a front frame.

The present disclosure has been made to address the above-described problem and provides an indoor unit for an air-conditioning apparatus that prevents condensation from occurring on a terminal end of a back air passage wall.

Solution to Problem

An indoor unit for an air-conditioning apparatus according to an embodiment of the present disclosure includes a main body attached to an attachment portion, a heat exchanger attached to the main body and configured to cause heat exchange to be performed between air and refrigerant, a fan attached to the main body and configured to send, into a room, air subjected to heat exchange in the heat exchanger, and a front frame attached to the main body by using a screw. The front frame forms a fan casing that accommodates the fan between the front frame and the main body and through which air sent by the fan passes. The fan casing has an air outlet through which air is blown out, between a front air passage wall on a front side of the fan casing and a back air passage wall on a back side of the fan casing. The back air passage wall has, at a downstream terminal end, a recess into which the screw is inserted. The indoor unit further includes a screw cover covering the screw and attached to the recess. The screw cover has a hollow passing through in a laterally extending direction, and a chamber is formed by the hollow being held between side walls located on both sides of the recess in the front frame.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, the screw cover attached to the recess formed at the terminal end of the back air passage wall has the hollow, and the chamber is formed by the hollow being held between the side walls located on both sides of the recess. Thus, indoor air hardly enters the inside of the screw cover. Accordingly, condensation can be prevented from occurring when cold air is blown onto an upper portion of the screw cover.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a circuit diagram of an air-conditioning apparatus 1 according to Embodiment 1 of the present disclosure.

FIG. 2 is an assembly perspective view of an indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 3 is an exploded perspective view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 4 is a sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 5 is an enlarged sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 6 is an enlarged view of a recess 43 of a front frame 40 according to Embodiment 1 of the present disclosure.

FIG. 7 is an enlarged perspective view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 8 is an exploded perspective view of a screw cover 50 and the recess 43 according to Embodiment 1 of the present disclosure.

FIG. 9 is a perspective view of the screw cover 50 according to Embodiment 1 of the present disclosure.

FIG. 10 is a sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

FIG. 11 is an enlarged sectional view of an indoor unit 100 according to a comparative example.

FIG. 12 is an enlarged sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure.

DESCRIPTION OF EMBODIMENT Embodiment 1

Hereinafter, an embodiment of an indoor unit for an air-conditioning apparatus according to the present disclosure will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram of an air-conditioning apparatus 1 according to Embodiment 1 of the present disclosure. As FIG. 1 illustrates, the air-conditioning apparatus 1 is an apparatus for conditioning indoor air and includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 includes, for example, a compressor 6, a flow-switching device 7, an outdoor heat exchanger 8, an outdoor fan 9, and an expansion unit 10. The indoor unit 3 includes, for example, a heat exchanger 11 and a fan 12.

A refrigerant circuit 4 includes the compressor 6, the flow-switching device 7, the outdoor heat exchanger 8, the expansion unit 10, and the heat exchanger 11 being connected to one another by refrigerant pipes 5. The compressor 6 sucks low-temperature and low-pressure refrigerant, compresses the sucked refrigerant to bring the refrigerant into a high-temperature and high-pressure state, and discharges the refrigerant. The flow-switching device 7 switches directions in which refrigerant flows in the refrigerant circuit 4 and is, for example, a four-way valve. The outdoor heat exchanger 8 causes heat exchange to be performed between, for example, outdoor air and refrigerant. The outdoor heat exchanger 8 operates as a condenser during a cooling operation and operates as an evaporator during a heating operation. The outdoor fan 9 is a device for sending outdoor air to the outdoor heat exchanger 8.

The expansion unit 10 is a pressure-reducing valve or an expansion valve for reducing the pressure of refrigerant to expand the refrigerant. The expansion unit 10 is, for example, an electronic expansion valve of which opening degree is regulated. The heat exchanger 11 causes heat exchange to be performed between, for example, indoor air and refrigerant. The heat exchanger 11 operates as an evaporator during the cooling operation and operates as a condenser during the heating operation. The fan 12 is a device for sending indoor air to the heat exchanger 11.

(Operation Mode, Cooling Operation)

Next, an operation mode of the air-conditioning apparatus 1 will be described. First, a cooling operation will be described. In the cooling operation, the refrigerant sucked into the compressor 6 is compressed by the compressor 6 and discharged from the compressor 6 in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 6 in such a high-temperature and high-pressure gas state passes through the flow-switching device 7, flows into the outdoor heat exchanger 8 operating as a condenser, and exchanges heat with the outdoor air sent by the outdoor fan 9 to be condensed and liquefied in the outdoor heat exchanger 8. The condensed refrigerant in a liquid state flows into the expansion unit 10 and is expanded and reduced in pressure to turn into a low-temperature and low-pressure two-phase gas-liquid state in the expansion unit 10. The refrigerant in such a two-phase gas-liquid state then flows into the heat exchanger 11 operating as an evaporator and exchanges heat with the indoor air sent by the fan 12 to be evaporated and gasified in the heat exchanger 11. At this time, the indoor air is cooled, and air cooling is performed in a room. The evaporated refrigerant in a low-temperature and low-pressure gas state passes through the flow-switching device 7 and is sucked into the compressor 6.

(Operation Mode, Heating Operation)

Next, a heating operation will be described. In the heating operation, the refrigerant sucked into the compressor 6 is compressed by the compressor 6 and discharged from the compressor 6 in a high-temperature and high-pressure gas state. The refrigerant discharged from the compressor 6 in such a high-temperature and high-pressure gas state passes through the flow-switching device 7, flows into the heat exchanger 11 operating as a condenser, and exchanges heat with the indoor air sent by the fan 12 to be condensed and liquefied in the heat exchanger 11. At this time, the indoor air is heated, and air heating is performed in a room. The condensed refrigerant in a liquid state flows into the expansion unit 10 and is expanded and reduced in pressure to turn into a low-temperature and low-pressure two-phase gas-liquid state in the expansion unit 10. The refrigerant in such a two-phase gas-liquid state then flows into the outdoor heat exchanger 8 operating as an evaporator and exchanges heat with the outdoor air sent by the outdoor fan 9 to be evaporated and gasified in the outdoor heat exchanger 8. The evaporated refrigerant in a low-temperature and low-pressure gas state passes through the flow-switching device 7 and is sucked into the compressor 6.

(Indoor Unit 3)

FIG. 2 is an assembly perspective view of the indoor unit 3 according to Embodiment 1 of the present disclosure, and FIG. 3 is an exploded perspective view of the indoor unit 3 according to Embodiment 1 of the present disclosure. FIG. 4 is a sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure. Next, the indoor unit 3 will be described. As FIGS. 2 to 4 illustrate, the indoor unit 3 has a main body 20, a vertical airflow deflection plate 30, the heat exchanger 11, the fan 12, a front frame 40, and screw covers 50.

(Main Body 20, Vertical Airflow Deflection Plate 30, Front Frame 40)

The main body 20 is to be attached to an attachment portion 15 such as a wall. The vertical airflow deflection plate 30 is attached to the main body 20 and rotates to adjust vertically the flow direction of the air sent by the fan 12. The front frame 40 is attached to the main body 20 by using screws 60, covers the heat exchanger 11 and the fan 12, for example, and has an air outlet 41 from which air is blown out. A fan casing 21 accommodating the fan 12 and forming an air passage through which the air sent by the fan 12 passes is formed between the main body 20 and the front frame 40. An upper portion of the front frame 40 has an opening that is to be an air inlet 42 into which indoor air is sucked. In addition, two recesses 43 are formed in a lower portion of the front frame 40.

(Heat Exchanger 11, Fan 12)

The heat exchanger 11 is attached to the main body 20 and causes heat exchange to be performed between indoor air and refrigerant as described above. The heat exchanger 11 is disposed in upper part of a region between the main body 20 and the front frame 40 and performs heat exchange of the indoor air sucked from the air inlet 42. The fan 12 is attached to the main body 20 and is a device for sending indoor air to the heat exchanger 11 as described above. The fan 12 is disposed downstream of the heat exchanger 11 in the region between the main body 20 and the front frame 40, and the fan 12 sends the indoor air sucked from the air inlet 42 to the heat exchanger 11 and blows the air subjected to heat exchange in the heat exchanger 11 through the air outlet 41.

(Fan Casing 21)

FIG. 5 is an enlarged sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure. Here, the fan casing 21 formed between the main body 20 and the front frame 40 and forming the air passage will be described. As illustrated in FIG. 5, the fan casing 21 is made up of a front air passage wall 22 on the front side and a back air passage wall 23 on the back side. The back air passage wall 23 has a main body-side air passage wall 23 a formed in the main body 20 and a frame-side air passage wall 23 b formed in the front frame 40. The main body-side air passage wall 23 a and the frame-side air passage wall 23 b are arranged along the same line. That is, there is no difference in level between the main body-side air passage wall 23 a and the frame-side air passage wall 23 b, and the main body-side air passage wall 23 a and the frame-side air passage wall 23 b are formed in a continuous manner. Regarding the front frame 40, a terminal end of the frame-side air passage wall 23 b downstream in the flow of air is connected to a bottom 44 that is a bottom face of the front frame 40.

(Recess 43)

FIG. 6 is an enlarged view of the recess 43 of the front frame 40 according to Embodiment 1 of the present disclosure. As FIG. 6 illustrates, in a lower portion of the front frame 40, for example, two recesses 43 are formed. In each of the recesses 43, a screw hole into which the screw 60 is inserted is formed, and the main body 20 and the front frame 40 are fixed to one another by the screw 60 being inserted into and screwed with the screw hole with the main body 20 fitting to the front frame 40.

Here, in the front frame 40, the recess 43 is formed at the downstream terminal end of the frame-side air passage wall 23 b, and the screw 60 is inserted thereinto. The recess 43 is formed by cutting out part of the frame-side air passage wall 23 b and part of the bottom 44. Air passage wall-side steps 43 b are formed in side edge portions of a portion where the recess 43 is formed in the frame-side air passage wall 23 b, and bottom-side steps 43 a are formed in side edge portions of a portion where the recess 43 is formed in the bottom 44. In addition, a horizontal step 43 c is formed in a horizontal edge of a portion where the recess 43 is formed in the frame-side air passage wall 23 b. Both sides of the recess 43 are side walls 45 in the front frame 40. Pairs of upper and lower catching portions 46 are provided inside the recess 43.

(Screw Cover 50)

FIG. 7 is an enlarged perspective view of the indoor unit 3 according to Embodiment 1 of the present disclosure, and FIG. 8 is an exploded perspective view of the screw cover 50 and the recess 43 according to Embodiment 1 of the present disclosure. As FIGS. 7 and 8 illustrate, the screw cover 50 is attached to the recess 43 formed at the terminal end of the frame-side air passage wall 23 b in the back air passage wall 23. Here, the screw cover 50 is shaped so as to form part of the front frame 40 by being embedded in the recess 43 of the front frame 40, and the design of the indoor unit 3 is thereby improved. A cutout 50 a is formed in a rear portion of the screw cover 50. When removing the screw cover 50, a personnel such as an installer engages a tip of a screwdriver, a human nail, or other tools in the cutout 50 a, thereby being able to separate the screw cover 50 and the front frame 40 from one another. Here, two screw covers 50 are provided and attached to two recesses 43 on a one-on-one basis.

FIG. 9 is a perspective view of the screw cover 50 according to Embodiment 1 of the present disclosure. As FIG. 9 illustrates, the screw cover 50 has a bottom face 51, an air passage face 52, a partition wall 53, and engaging portions 57. The bottom face 51 forms part of the bottom 44 of the front frame 40 and is, for example, a plate-shaped part. Bottom face-side steps 51 a are formed in both side edge portions of the bottom face 51. The air passage face 52 is connected to the bottom face 51 and forms part of the frame-side air passage wall 23 b in the back air passage wall 23, thereby receiving the air sent by the fan 12. The air passage face 52 is, for example, a curved part. Air passage face-side steps 52 a are formed in both side edge portions of the air passage face 52.

The partition wall 53 is disposed on the front side relative to the screw 60, connects the bottom face 51 and the air passage face 52 to one another, and forms, in the screw cover 50, a hollow 54 passing through in the laterally extending direction. A boundary step 53 a is formed at the boundary between the air passage face 52 and the partition wall 53. When the screw cover 50 has been attached to the recess 43, a chamber 55 is formed by the hollow 54 being held between the side walls 45 located on both sides of the recess 43 in the front frame 40 (refer to FIG. 10). The engaging portions 57 extend horizontally from the partition wall 53 and are caught by the catching portions 46 formed inside the recess 43 of the front frame 40. By the engaging portions 57 being caught by the catching portions 46, the screw cover 50 fits in and fixed to the recess 43 of the front frame 40.

FIG. 10 is a sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure as viewed from the front lower side when the back air passage wall 23 is cut horizontally. Next, how the screw cover 50 is attached to the recess 43 will be described. As FIG. 10 illustrates, when the screw cover 50 is attached to the recess 43, the air passage face-side steps 52 a fit to the air passage wall-side steps 43 b on a one-on-one basis, and the horizontal step 43 c and the boundary step 53 a fit to one another; thus, the air passage face 52 is attached to the back air passage wall 23. In addition, the bottom-side steps 43 a fit to the bottom face-side steps 51 a on a one-on-one basis, and the bottom face 51 is thereby attached to the bottom 44. Thus, a portion where the screw cover 50 and the recess 43 fit to one another has a spigot joint shape. Accordingly, it is possible to suppress secondary air such as cold air or indoor air from entering the chamber 55 inside the screw cover 50. In addition, although a slight amount of indoor air may enter a space 56 between the screw 60 and the partition wall 53 from a portion where the main body 20 and an installation plate fit to one another at the back side of the indoor unit 3 through a gap (refer to the arrow in FIG. 10), such indoor air hardly enters the inside of the screw cover 50 due to the partition wall 53.

FIG. 11 is an enlarged sectional view of an indoor unit 100 according to a comparative example. Here, for facilitating understanding of an action of the indoor unit 3 according to Embodiment 1 of the present disclosure, the indoor unit 3 will be described in comparison with the indoor unit 100 according to the comparative example. First, the indoor unit 100 according to the comparative example will be described. As FIG. 11 illustrates, in the indoor unit 100 according to the comparative example, a tape strip 170 having a water absorption effect is stuck to a terminal end of a back air passage wall 123 of a fan casing 121. During the cooling operation, the air cooled by a heat exchanger and air in a room stay at the terminal end of the back air passage wall 123, and water in the air is thereby solidified to cause condensation there. The indoor unit 100 according to the comparative example suppresses condensation water 180 from dripping by the tape strip 170 absorbing the condensation water 180. In the indoor unit 100 according to the comparative example, a terminal end of the fan casing 121 protrudes frontward, and a screw cover 150 covering a screw 160 is disposed at a position apart from the terminal end of the fan casing 121.

FIG. 12 is an enlarged sectional view of the indoor unit 3 according to Embodiment 1 of the present disclosure. Next, the indoor unit 3 according to Embodiment 1 will be described. As FIG. 12 illustrates, during the cooling operation, the air cooled by the heat exchanger 11 is blown onto the air passage face 52 of the screw cover 50 forming part of the back air passage wall 23. On the other hand, a slight amount of indoor air flows into the space 56 between the screw 60 and the partition wall 53. However, the partition wall 53 prevents the indoor air from reaching the chamber 55 formed inside the screw cover 50. Thus, the chamber 55 exhibits a heat insulation effect, and it is thereby possible to suppress condensation from occurring on the air passage face 52 and the bottom face 51 and in the space 56 where indoor air is likely to stay.

As described above, according to Embodiment 1, the screw cover 50 attached to the recess 43 formed at the terminal end of the back air passage wall 23 has the hollow 54, and the chamber 55 is formed by the hollow 54 being held between the side walls 45 located on both sides of the recess 43. Thus, indoor air hardly enters the inside of the screw cover 50. Accordingly, condensation can be suppressed from occurring when cold air is blown onto an upper portion of the screw cover 50. Moreover, compared with the indoor unit 3 according to the comparative example illustrated in FIG. 11, the indoor unit 3 according to Embodiment 1 does not need a tape strip 170, and costs can thereby be reduced. Furthermore, it is possible to suppress condensation from occurring not only on the air passage face 52 of the screw cover 50 but also on the bottom face 51 of the screw cover 50 even if cold air is blown onto the bottom face 51.

In the indoor unit 3 according to the comparative example illustrated in FIG. 11, the terminal end of the fan casing 121 protrudes, and indoor air is thereby drawn into and stays in a region below the terminal end of the fan casing 121. Thus, condensation occurs on the terminal end of the fan casing 121, condensation water drips, and the quality of the indoor unit 100 may deteriorate. In contrast, in the indoor unit 3 according to Embodiment 1, the fan casing 21 is made up of the main body 20 and the front frame 40, and the size of the screw cover 50 itself is increased. Thus, the distance D between the frame-side air passage wall 23 b and the vertical airflow deflection plate 30 is short (refer to FIG. 5), and the air outlet 41 is narrow. Accordingly, a diffusion effect operates on the air sent by the fan 12, the quantity of the air blown out from the air outlet 41 increases, and the retention of indoor air caused by indoor air being drawn is thereby reduced. Thus, the indoor unit 3 according to Embodiment 1 can reduce the occurrence of condensation.

As described above, the portion where the screw cover 50 and the recess 43 fit to one another has the spigot joint shape. Thus, it is possible to suppress secondary air such as cold air or indoor air from entering the chamber 55 inside the screw cover 50.

REFERENCE SIGNS LIST

1 air-conditioning apparatus 2 outdoor unit 3 indoor unit 4 refrigerant circuit 5 refrigerant pipe 6 compressor 7 flow-switching device 8 outdoor heat exchanger 9 outdoor fan 10 expansion unit 11 heat exchanger 12 fan 15 attachment portion 20 main body 21 fan casing 22 front air passage wall 23 back air passage wall 23 a main body-side air passage wall 23 b frame-side air passage wall 30 vertical airflow deflection plate 40 front frame 41 air outlet 42 air inlet 43 recess 43 a bottom-side step 43 b air passage wall-side step 43 c horizontal step 44 bottom 45 side wall 46 catching portion 50 screw cover 50 a cutout 51 bottom face 51 a bottom face-side step 52 air passage face 52 a air passage face-side step 53 partition wall 53 a boundary step 54 hollow 55 chamber 56 space 57 engaging portion 60 screw 100 indoor unit 121 fan casing 123 back air passage wall 150 screw cover 160 screw 170 tape strip 180 condensation water 

1. An indoor unit for an air-conditioning apparatus, the indoor unit comprising: a main body attached to an attachment portion; a heat exchanger attached to the main body and configured to exchange heat between air and refrigerant; a fan attached to the main body and configured to send, into a room, air subjected to heat exchange in the heat exchanger; a front frame attached to the main body by using a screw, the front frame forming a fan casing that accommodates the fan between the front frame and the main body and through which air sent by the fan passes and an air outlet through which air is blown out, and the back air passage wall on a back side of the fan casing having, at a downstream terminal end, a recess into which the screw is inserted; and a screw cover covering the screw and attached to the recess, wherein the screw cover has a hollow passing through in a laterally extending direction, and a chamber is formed by the hollow being held between side walls located on both sides of the recess in the front frame.
 2. The indoor unit for an air-conditioning apparatus of claim 1, wherein the screw cover has: a bottom face forming part of a bottom of the front frame; an air passage face connected to the bottom face, forming part of the back air passage wall, and receiving air sent by the fan; and a partition wall disposed on a front side relative to the screw and connecting the bottom face and the air passage face to one another, wherein an internal space surrounded by the bottom face, the air passage face and the partition wall is the hollow.
 3. The indoor unit for an air-conditioning apparatus of claim 2, wherein, in an edge portion of a portion where the recess is formed in the back air passage wall, an air passage wall-side step is formed, wherein, in an edge portion of the air passage face, an air passage face-side step is formed, and wherein the air passage face-side step and the air passage wall-side step fit to one another, and the air passage face is attached to the back air passage wall.
 4. The indoor unit for an air-conditioning apparatus of claim 2, wherein, in an edge portion of a portion where the recess is formed in the bottom, a bottom-side step is formed, wherein, in an edge portion of the bottom face, a bottom face-side step is formed, and wherein the bottom-side step and the bottom face-side step fit to one another, and the bottom face is attached to the bottom. 